Circuit-closer for burglar-alarm systems



(No Model.)

- A. STROMBERG.

CIRCUIT CLOSER FOR BURGLAR ALARM SYSTEMS.

No. 530,975. Patented Dec. 18, 1894.

UNITED STATES PATENT OFFICE.

ALFRED STROMBERG, OF CHICAGO, ILLINOIS.

CIRCUIT-CLOSER FOR BURGLAR-ALARM SYSTEMS.

SPECIFICATION forming part of Letters Patent No. 530,975, dated December18, 1894.

Application filed May 24, 1894. Serial Fri-512,339. (No model.)

To all whom it may concern.-

Be it known that I, ALFRED SrRoMBERe, a citizen of the United States,residing at Ohicago, in the county of (look and State of Illinois, haveinvented a certain new and useful Improvement in Circuit-Closers forBurglar- Alarm Systems, (Case No.14) of which the following is a full,clear, concise, and exact description, reference being had to theaccompanying drawings, forming a part of this specification.

My invention relates to acircuit closer for burglar alarm systems, andits object is the provision of a circuit closer to be used in connectionwith the covering of an opening to be protected, whereby the removal ofthe covering will result in the opening of the circuit.

Heretofore, it has been proposed to provide a circuit closer inconnection with the covering of an opening, as, for instance, the sashof a window, so that so long as the sash remains closed the movableelement of a switch is maintained in position to complete an electriccircuit, the movable element assuming an alternative position to openthe circuit when the sash is opened. The objection to this constructionhas been that an instrument may be inserted between the sash and themovable element and the movable element maintained depressed while thesash may be opened without opening the circuit.

My invention herein,in its preferred form, comprises a movable elementadapted to be depressed when the sash, or other covering, is closed tomake contact with a circuit terminal and close the circuit, the movableelement at the same time making contact with a circuit terminal upon thesash to complete the circuit. If the contact between the movable elementand either of the circuit terminals be interrupted, the circuit will beopened.

My invention will be understood by reference to the accompanyingdrawings, in which Figure l is a diagrammatic View of a window equippedafter the manner of my invention, the sash being shown in its closedposition, Fig. 2 shows the sash partially opened. Fig. 3 shows themanner of applying my invention to a door. Fig. at is a side view of thecircuit closer. Fig. 5 is a sectional view thereof. Fig. 6 is an endview thereof.

Like letters refer to like parts in the several figures.

The circuit closer comprises a plunger a. pressed outward by a spring a,the end a of the plunger being adapted, when pressed inward, to makecontact with a pair of spring contacts Z) Z), which are electricallyconnected by means of a metallic ring 0 which surrounds the same. A ringof insulation 0 rests between the springs 12 b and the guide a in whichthe plunger moves, the lower ends of the springs being likewiseinsulated from the plate a by strips 0 c of insulating material. Theplunger a is thus normally insulated from the springs 19 b.

As shown in Fig. 1 the plunger is located on the window frame beneaththe lower edge of the sash, and is depressed, when the sash is closed,to make contact with springs 19 b. At the same timethe endof the plungermakes contact with a metallic plate 01 provided upon the sash. Thecircuit is shown completed through two such plungers, the plate d beingconnected with the plate 61 by conductor (1 Between the springs 19 b andground is located a resistance 6. The central office apparatus compriseselectro-magnets f f, in circuitwith a batteryf the magnetf being adaptedto close a local circuit to sound an alarm when an abnormally largecurrent flows,and the magnet f to close the local circuit when thecurrent flow ceases.

It the sashbe raised, the circuit will be opened by the movement of theplunger out of contact with the springs and the plate on the sash. If itbe attempted to ground the circuit, the resistance will be cut out andgive the alarm. If it be attempted to maintain the plunger depressed,the circuit will be opened between the plunger and the plate on thesash. If it be attempted to maintain the plunger in electricalconnection with the plate on the sash, the ascent of the plunger willbreak the connection with the springs,thereby opening the circuit.Instead of providing two such plungers in connection with the sash, butone may be employed, the circuit being completed through a pair ofco-acting contacts g g (indicated in dotted lines) when the sash isclosed.

As shown in Fig. 3, the plungers, when applied to a swinging covering,as a door, may best be located upon the edge upon which the hinges areprovided.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-

1. The combination with the covering of an opening, of a plate carriedthereon and connected in circuit, a plunger adapted to make contact withsaid plate and to be depressed when said covering is closed, and contactsprings adapted to be engaged by said plunger in the depressed positionthereof, said springs being connected in circuit, substantially asdescribed.

2. The combination with the covering of an opening, of a pair ofelectrically connected plates carried thereon, a pair of plungersadapted to make contact with said plates respectively, and to bedepressed when said covering is closed, and contact springs adapted tobe engaged by said plungers in the depressed positions thereof,substantially as described.

3. The combination with the covering of an opening, of a plate carriedthereon and connected in a protective circuit, a plunger adapted to makecontact with said plate and to be depressed when said covering isclosed, contact springs adapted to be engaged by said plunger in thedepressed position thereof, a resistance connected between said springsand ground, a local circuit at the central office containing a batteryand a signal device, an electro-magnet thereat adapted to close saidlocal circuit when the protective circuit is opened, and anelectro-magnet adapted to close said local circuit when said resistanceis cut from the circuit, substantially as described.

In witness whereof I hereunto subscribe my name this 11th day of May, A.D. 1894.

ALFRED STROMBERG.

Witnesses:

W. CLYDE J ONES, GEORGE L. GRAGG.

